Treatment of municipal solid waste

ABSTRACT

An apparatus and process for the separation, recovery and recycling of municipal solid waste (MSW) in which hot water  48  is added to shredded and homogenized MSW  2  as it enters a rotating feed preparation drum  34  equipped with internal lifter blades  36 . The blades  36  and rotation of the drum  34  cause mixing and pulping of the MSW before discharge into a rotating thermal processor  56  also equipped with lifter blades  58  and cone section  64 , and in which the moist MSW  2  is heated by heating the hot gases in the processor by a flame from burner  62  which converts the moisture in the MSW to steam. The steam permeates through the MSW as it is turned and lifted in the thermal processor  56 , causing further pulping. The now cooked and treated MSW  2  is then fed to a conveyor  68  for transportation to a trommel screen for the separation of recyclable components. In a preferred embodiment plugs  70, 72  of MSW are maintained at the exit and entrance to the thermal processor  56  and act to provide a seal to maintain and control the temperature within the thermal processor  56  by reducing the egress of steam therefrom.

The present invention relates to apparatus and process for theseparation, recovery and recycling of municipal solid waste (MSW) andthe like.

Traditionally MSW is disposed of by burying it in a landfill site.However, ecologically this is increasingly considered to be undesirable,since recyclable materials such as glass, metal and plastics have notbeen separated for recycling. Also, decomposing of the waste and leakageof hazardous materials can lead to environmental contamination, forexample methane. Sites suitable for landfill are also on the decline andgovernments are imposing high taxes on the disposal of waste in thismanner, in an attempt to control the over use of such sites and topromote safer more environmentally friendly disposal.

It is also known to incinerate MSW, the combustion of MSW produces ashand also noxious fumes which must be contained and further processed toenable their safer disposal. This method has the disadvantage that it isextremely expensive.

It is therefore desirable to provide a process for treating MSW whichaids the separation and recovery of inorganic and organic matter, in amore environmentally friendly and less expensive manner.

U.S. Pat. No. 5,190,226 discloses an apparatus and process for theseparation, recovery and recycling of MSW. In this process waste whichis delivered to a processing site is conveyed directly into a rotatingpressure vessel. An internal helix within the vessel splits the bags ofwaste and once the vessel is full it is closed, sealed and steam isintroduced until the required operating pressure and temperature isreached. The operating conditions are maintained for the required lengthof time, by regulating the steam input. During this process thecellulosic waste amongst the MSW becomes homogenised by steam saturationand the pulping action of the rotating vessel. Once the cycle iscomplete, the vessel is depressurised, the steam is removed and therotation of the vessel is reversed to emit the processed contentsthereof on to a conveyor. The conveyor then moves the waste into arotating trommel, where the pulp falls through the rotating screen ontoa conveyor. The separated pulp can then be used to produce fuel orcompost. The remaining waste within the trommel, then exits the trommelonto a conveyor for separation of recyclable material and with theremainder going to landfill.

However, the use of a pressure vessel has the disadvantage that theprocess is batch and not continuous in that the vessel takes 1 to 1½hours to fill and to bring up to the required temperature, and twofurther hours for the contents to be mixed at temperature and emptied.Therefore, there is a considerable length of time during which freshwaste cannot enter the pressure vessel. Also, because the vessels arepressurized special safety regulations are enforced for safe operationthereof, which requires considerable skilled man-power, which isunfeasible for smaller processing sites. Furthermore, the gauges on suchvessels are not always accurate and pressure may still be relativelyhigh when the vessel is opened, leading to scalding of attendantoperators. Furthermore, the vessel also requires a considerablemechanical drive in order to rotate it and in order to discharge itscontents at the end of the cycle, with consequential break-down of suchmechanisms leading to plant down time and the need to employ skilledservice engineers in order to maintain the equipment.

U.S. Pat. No. 5,556,445 (Quinn) describes a process for the treatment ofMSW without the use of a pressure vessel. In this process MSW is placedin a perforated drum fixed within a rotatable tube. The interior of thedrum is open to the atmosphere. Water is added to the waste and thewaste heated by feeding steam between the tube and drum. The rotation ofthe tube and heating of the MSW causes pulping of the organic matter inthe drum, which can then exit the drum through its perforations in orderto separate it from the inorganic matter of the waste.

However, this process has the disadvantage that the steam only heats theperiphery of the MSW, it is not evenly heated throughout its mass,thereby reducing the efficiency of the process. Furthermore, the organicfaction produced has a water content of between 35% to 70%, which isextremely wet and therefore will require further processing to reducethe water content to render the organic faction suitable for use as acomposter fuel. Also, some of the putrescible material will not dropthrough the perforations, causing pegging thereof thereby reducingefficiency and eventually making the process impossible to operate. TheMSW does not move through the drum by gravity, but requires internalfins to move the waste out of the drum.

It is an object of the present invention to provide a process andapparatus for the separation, recovery and recycling of MSW thatovercomes or alleviates the above described drawbacks.

In accordance with a first aspect of the present invention there isprovided an apparatus for treating municipal solid waste (MSW)comprising a moisture supply for adding moisture to said MSW, anon-pressurized feed preparation drum, a non-pressurized thermalprocessor located down-stream of said feed preparation drum, feedingmeans for conveying moistened MSW to be treated continuously throughsaid drum then said processor, agitating means for mixing the MSW in thefeed preparation drum, moisture evaporation means in the processor forsubstantially turning the moisture in the MSW to steam to cook the MSW,and agitating means for mixing the MSW in the thermal processor. Thishas the advantage that in a first stage moisture is mixed with the MSWand in a second stage that moisture is turned to steam to cook the MSWreducing any organic matter to a low-moisture pulp and allowing acontinuous throughput of MSW.

The drum and processor may be provided in-line in substantially the sameplane. This has the advantage that the height of the apparatus can bereduced, with the processor and drum being connected together by forexample mechanical seals enabling their independent rotation, or theycan be rigidly connected and may comprise separate internal agitationmeans to independently adjust the speed of mixing in each stage of theprocess.

The moisture evaporation means is preferably a source of hot gas whichheats the hot pulped waste as it is lifted by the agitation means intothe hot gas flow and which converts the moisture to steam to pulp andcook the waste and shrink plastics in the waste as the MSW moves downthe processor through the mixture of hot gas and steam.

The apparatus may comprise a buffer storage hopper located upstream ofthe feed preparation drum for receiving MSW to be treated and providinga column of MSW to be fed into the feed preparation drum, the bufferstorage hopper having a push floor feeder at its base for directing MSWinto the feed preparation drum.

The feed preparation drum may extend or be adapted to extend at a slightangle to the horizontal plane such that its inlet is lower than itsoutlet. This enables excess moisture in the drum to drain towards theinlet end of the drum, whereat it can be held in a reservoir.

The apparatus may comprise a discharge chamber located between the feedpreparation drum and thermal processor for receiving moistened MSWdischarged from the feed preparation drum and providing a column ofmoist MSW to be fed to the thermal processor, the column of moist MSWproviding a plug of moist MSW at entrance to the thermal processor, thedischarge chamber may have a push floor feeder at its base for directingsaid moist MSW into the thermal processor.

The apparatus may comprise a thermal processor discharge chamber locateddownstream of the thermal processor for receiving the cooked MSW fromthe thermal processor and for providing a column of MSW to be dischargedfrom the apparatus, the column providing a plug of cooked MSW at theoutlet to the thermal processor, the thermal processor discharge chambermay have a push floor feeder at its base for directing MSW out of theapparatus.

In a preferred embodiment stocking means are provided for forming acolumn of MSW at the entrance and/or exit to the thermal processor. TheMSW plugs provide a seal at the entrance and/or exit to the thermalprocessor which enables steam to be retained. Any steam which doespermeate back through the apparatus preheats the MSW before entry intothe thermal processor and/or feed preparation drum.

The agitating means may be in the form of means for rotating the drum orprocessor, and may be provided with internal lifting blades. Such meansensure thorough mixing of the moisture/steam within the MSW, inducetearing of the MSW and help to move the MSW through the drum/processor.

The interior of the thermal processor may taper inwardly towards itsexit. This has the advantage that as the MSW is reduced in volume by thecooking and pulping thereof the volume fill of the processor ismaintained, ensuring that any plastics present in the MSW are heated toinduce shrinkage.

In accordance with a second aspect of the present invention there isprovided a process for treating municipal solid waste (MSW) comprisingthe steps of:

-   -   adding moisture to the MSW;    -   conveying the MSW through a non-pressurized feed preparation        drum;    -   agitating said MSW as it is conveyed through the drum to moisten        the MSW and to initilize pulping of organic matter present in        the MSW;    -   conveying the moistened MSW from the drum to a non-pressurized        thermal processor;    -   agitating said moist MSW as it is conveyed through the thermal        processor;    -   heating the moist MSW in the processor to substantially turn the        moisture to steam to cook the MSW.

The MSW may be stocked upon its entrance into and/or its exit from thethermal processor to provide a plug of MSW at inlet and/or outlet to thethermal processor, this provides a seal at the entrance and/or exit ofthe thermal processor to help retain the heat therein and maintain therequired temperature within.

The MSW may be shredded and homogenized prior to the process in order toreduce the size of waste entering the feed preparation drum, therebyreducing the amount of time required for the process, the size of thedrum and processor and reducing potential damage to the apparatus.

The moisture may be preheated before it is added to the MSW, thisincreases the efficiency of the feed preparation step before entry intothe thermal processor.

The temperature in the thermal processor is preferably raised up to 400°C. at its outlet and up to 100° C. at its inlet, this ensures pulping ofthe waste. This is higher than the temperatures described in U.S. Pat.No. 5,556,445 (Quinn) whose operating temperature is only in the rangeof 100° C. to 260° C. The required temperature of the processor may beset to achieve the required degree of cleaning of the waste, in that itmay be adjusted to achieve sterilization of the waste, if required. Theparameters of the MSW at various stages of the process may be monitoredand the measurements used to adjust the flow of MSW.

By way of example only a specific embodiment of the present inventionwill now be described with reference to the accompanying drawings, inwhich: —

FIG. 1 is a schematic view of municipal solid waste (MSW) collection andfeed pre-treatment process adapted in accordance with the presentinvention;

FIG. 2 is a schematic view of an apparatus constructed in accordancewith the present invention for treating MSW delivered from the processof FIG. 1; and

FIG. 3 is a schematic view, similar to that of FIG. 2 of a secondembodiment of apparatus for treating MSW.

Referring to FIG. 1 municipal solid waste (MSW) 2 is delivered to aprocessing plant by for example a refuse vehicle 4 from which it istipped into a hopper 6 feeding an inspection/picking belt 8. Extremelylarge items of MSW, such as for example microwave ovens, carpets andbicycles etc may be removed from the MSW at this stage. The remainingMSW on the inspection/picking belt 8 discharges into a primary shredder10 which tears open bin bags and shreds the waste to items of a width ofless than 300 mm. The waste is then conveyed via a conveyor 12 into awaste tipping hall 14 for homogenisation in a known manner.

The waste is collected from the tipping hall 14 using a crane grab 16operable to enable the deposit of waste into a hopper and belt weighfeeder 18 at a rate of 4000 to 6000 Kg (4 to 6 tonnes) per hour. Thefeeder 18 feeds a screen 20 through which waste sized at less than 200mm can fall to a conveyor 22, on which it is conveyed to the next stageof the process described further hereinunder. Waste sized greater than200 mm is conveyed along the screen 20 and into a secondary shredder 24.The secondary shredder 24 shreds the waste to a size of less than 200 mmand discharges this now further shredded waste down onto said conveyor22 for transportation to the next stage of the process.

Conveyor 22 conveys the homogenised shredded waste into the firstsection of a processing plant, as best illustrated in FIG. 2, comprisinga non-pressurized, preheated, thermally clad buffer storage hopper 26into which the waste is deposited and in which the waste is thenpreheated by hot air source 27 up to 95° C. High level probe 28 is usedto monitor the infeed of waste from the conveyor 22 into the hopper 26,whilst low level probe 30 is used to monitor the outflow of waste fromthe hopper 26 to the next stage of the process. Measurement from theprobes 28, 30 are used to adjust in the input of waste from the conveyor22 into the hopper 26, in that if the level of waste falls below lowlevel probe 30 additional waste is added to the hopper, and once wastereaches the level of probe 28 the waste input is halted. The entrance tothe hopper 26 is fitted with an air lock seal valve 25, which is openedwhen the waste is input from the conveyor 22 and closed to seal thehopper when the input is ceased. The column of waste in the hopperprovides gravity feed assistance to the flow of waste to the next stageof the treatment of the waste, additionally the base of the storagehopper 26 contains a push floor feeder 32 which discharges the waste ata controlled rate from the hopper 26 into the entrance of a feedpreparation drum 34. The feed preparation drum comprises a thermallyclad rotatable drum with a series of internal lifter blades along itslength for lifting, tearing, pulping and advancing the waste materialalong its length. The feed preparation drum 34 is fitted with mechanicalseals 38 at its inlet and outlet ends to enable its rotatable mountingbetween the inlet hopper 26 and a feed preparation drum outlet/thermalprocessor inlet chamber 40.

The push floor feeder 32 is designed to fit snugly with the mechanicalseal 38 at the entrance to the feed preparation drum 34 and is set at anangle, downwardly inclined towards the entrance to the feed preparationdrum 34 to enable a smooth flow of waste material into the drum. The lowlevel probe 30 monitors the waste in this region and enables the controlof the feed of the feeder 32 to adjust the flow of waste into the drum34 in order to prevent blockage thereof.

The drum 34 is rotated on tyres and wheels 42 and is operated through avariable speed chain drive 44 capable of running at a relatively highspeed. The drum 34 is tiltable by plus or minus a few degrees X fromhorizontal by a tilting mechanism 46. The drums drive and the tiltingmechanism are controlled based on measurement taken from the probes 28,30 to facilitate the required throughput of waste.

As the waste passes from the hopper 26 into the wet feed preparationdrum 34 it is sprayed at a controlled rate with a mist of water 48 whichis supplied from a tank of water 50. The temperature of the water canalso be adjusted depending on the detected temperature of the MSW.

Chemical additives 52 which assist with the breakdown of certaincomponents in the waste may be added to the water if required.

Once inside the wet feed preparation drum 34 the waste is lifted by therotation of the drum 34 and the action of the lifter blades 36 and isthoroughly mixed and pulped as it passes along the length of the drum 34before discharging into the thermal processor inlet chamber 40. Inletchamber 40 is equipped with high and low level probes 28 and 30 whichmonitor the levels of the waste within the inlet chamber 40, and asabove are used to adjust the flow of waste.

The base of the chamber 40 is fitted with a further push floor feeder 54which discharges the waste at a controlled rate from the inlet chamber40 into a thermal processor 56 and which is disposed and controlledsimilarly to feeder 32.

The thermal processor 56 comprises a thermally clad rotatable drum witha series of internal lifter blades 58 along its entire length, whichlift and advance the waste through the drum as it rotates. The thermalprocessor 56 is fitted with mechanical seals 38 at each end to enableits rotatable mounting between its inlet chamber 40 and a thermalprocessor outlet chamber 60 provided at the outlet to the thermalprocessor 56. The thermal processor 56 is rotated on further tyres andwheels 42 and is operated through a further variable speed chain drive44 capable of running at a relatively high speed. The thermal processor56 is tiltable by plus or minus a few degrees X from horizontal by afurther tilting mechanism 46. The drive and tilt are adjusted to achievethe required throughput.

A gas burner and air inlet unit 62 is mounted in the outlet chamber 60whose gas flame output is injected through a baffle spreading canfeeding into the discharge end of the thermal processor 56. As the hotpulped waste is fed into the entrance of the thermal processor 56, fromthe push floor feeder 54, the waste is further lifted by the rotation ofthe thermal processor 56 and the action of its lifter blades 58 causingfurther mixing and pulping as it passes along the length of the thermalprocessor 58 before discharge into the outlet chamber 60. Additionallythe gas flame injected into the rotating thermal processor 58 by the gasburner unit 62 heats the air and converts the hot water in the pulpedwaste into steam raising the temperature at the outlet zone 64 of thethermal processor to between 250° C. to 400° C. and the inlet end 38 toapproximately 100° C. The conversion of the moisture in the hot pulpedwaste into steam further pulps the waste and cooks the waste before itsdischarge into the outlet chamber 60; with the steam and input air fullypermeating the waste as it is lifted and advanced through the thermalprocessor.

The outlet zone 64 of the thermal processor 58 comprises an internalcone body 64, which gradually tapers towards the outlet chamber 60 togradually reduce the internal diameter of the thermal processor 58towards its outlet end 60. This acts to further concentrate the heat inthe outlet zone of the thermal processor, as the waste reduces in volumeas any cellulosic material is converted into a low moisture pulp andwaste such as plastics are shrivelled, and cans and glass scrubbedclean. The volume of the waste is typically reduced in volume up to by60% by this stage of the process.

The outlet chamber 60 is also fitted with high and low level probes 28and 30 which as in the previous chambers act to monitor and control thelevel of the waste therein.

The waste is discharged from the outlet chamber 60 by a further pushfloor feeder 66 onto a belt conveyor 68 for transfer onto a trommelscreen where the waste can be separated into component recyclable partsusing conventional equipment in a known manner.

The waste in the outlet chamber 60 is stocked to provide a plug of wastematerial 70 by controlling the flow of waste using the measurementsobtained from the high and low level probes 28 and 30 the column ofwaste between the probes providing a seal at the outlet to the thermalprocessor. The waste in the inlet chamber 40 is similarly stocked toprovide a plug of higher density waste at the inlet to the thermalprocessor 58. The throughput of the waste is adjusted by controlling theinput of waste into the thermal hopper 26 from the conveyor 22 and byadjusting the speed of operation of the push floor feeds 32, 54 and 66.Furthermore, the speed of rotation of the wet feed preparation drum 34and thermal processor 56 and their angle of tilt can be adjusted, aswell as the amount of water added. The two plugs of waste 70 and 72 atthe outlet and inlet ends of the thermal processor 56 act to provide aseal to maintain and control the temperature within the thermalprocessor, by reducing the egress of steam and heat from the thermalprocessor 56. The various mechanical seals 38 also act to prevent theegress of steam to the environment.

The outlet chamber 60 is fitted with an explosion vent/disc (notillustrated) at atmospheric pressure to vent explosive gasses, forexample if there is a waste gas bottle within the waste which couldexplode during treatment of the waste, thereby maintaining the thermalprocessor at substantially atmospheric pressure. The outlet chambers 60and 40 is further fitted with a temperature gauge (not illustrated) andviewing glass window (not illustrated) to enable an operator to observethe waste treatment and to initiate a manual override if necessary.

Any heat or steam which does permeate upstream of the waste acts topreheat the waste in the wet feed preparation drum 34 and the bufferstorage hopper 26. Excess steam and heat is extracted from the bufferstorage hopper 26 and the inlet chamber 40 by extraction lines 74 and 76via the action of extraction fan 78 and damper 80, which latterrecirculates the gas/steam back to the outlet chamber 60 and directs anysurplus to a scrubber 82 for thermal efficiency. An air separator 73 inthe extraction lines removes any films, plastics, or particles entrainedin said gas/stream and ejects such via rotary valve 75 into a skip 77.The air lock, slide valve 25 preventing the extraction line merelydrawing air from the external environment. The scrubber 82 cleans thewaste steam/gas to reduce the emissions before discharge through stack84 via the action of extractor fan 86, to an acceptable level to meetthe environmental regulations. The hot water in the scrubber 82 is thentreated with chemicals before it is transferred to the water tank 50which supplies water 48 to the waste entering the wet feed preparationdrum 34. The water tank 50 is additionally supplied with water from amains supply 88. This gives rise to an environmentally friendly system,in that a substantial portion of the excess heat/moisture is recycled.

Tests on this process and apparatus show that during processing thevolume of the waste is reduced to approximately 60% with 85 to 90% ofthe thermally treated waste suitable for recycling and only an inertresidue of 10 to 15% needing to go to landfill (the percentage isdependent on the initial content of the input of MSW to the process).The cooked waste has the following products: —

-   -   cellulosic pulp having a moisture content of up to 15% which is        highly suitable for further processing to produce a fuel or        compost;    -   steel and aluminium cans which have been cleaned and delabelled;    -   glass bottles which have been cleaned and delabelled;    -   plastic bottles and bags which have been shrunk and thereby        reduced in volume; and    -   inert landfill material.

Although the feed drum and thermal processor have been described asbeing vertically spaced apart via the interposition of a feedpreparation drum outlet/thermal processor inlet chamber 40, it is to beunderstood that the chamber 40 could be omitted and the drum 34 andprocessor 56 provided instead directly in-line, as best illustrated inFIG. 3. In this embodiment the drum and processor are interconnected bytheir mechanical seals 38, the drum 34 by this means feeds the warmedmoist waste directly into the thermal processor 56 for cooking and isrotatable independently of the thermal processor 56. The drum 34 in useis turned faster than the processor 56 facilitating complete mixing ofthe water and waste and initilisation of the pulping process. Althoughthe processor and drum have been described as being directly adjacent,they could be provided in line, but spaced apart by a chamber betweentheir respective mechanical seals through which the waste can pass,without direct agitation. Furthermore, the mechanical seals could beomitted and the drum and processor formed as a unitary chamber, with thepreparation of the waste by adding water and agitating taking part inthe front end of that chamber, and the cooking taking part downstreamthereof at the outlet end to that chamber.

Furthermore, although the feed preparation drum has been illustrated asextending in a horizontal plane, this drum could in an alternativeembodiment extend at a slight angle to the horizontal plane, such thatits inlet is lower than its outlet. By this means any excess moisturedrains towards the inlet to provide a reservoir at the inlet end of thedrum. The reservoir providing a source of moisture for the MSW asrequired. A drain can be provided to remove excess moisture from thereservoir. The backward inclination to the MSW passing through the draincan be selectively provided by the tilting mechanism depending onconditions detected, or can be a permanent feature of the drum by fixingthe drum in position at an angle, or by providing an inclination to itsinternal chamber. The tilting mechanism may be omitted.

It is to be understood that the invention is not limited to thespecifically described apparatus and other arrangements will be apparentto one skilled in the art which facilitate a continuous process withthermal cooking and mixing at substantially atmospheric pressure. Forexample, although the agitation of the waste has been described as beingby rotating the drum/processor and via the action of internal fixedlifter blades, other forms of agitation means may be additionally oralternatively provided in that the drum/processor may be fixed androtatable shredders may be provided inside the drum/processor. Althougha gas burner unit has been described as the heat source for convertingmoisture in the waste to steam, the applied heat could for example be anoil burner or other radiant heat sources. Although heat is injected intothe outlet end of the thermal processor, such heat may additionally, oralternatively be injected through the walls of the thermal processordirectly, via separate injectors or which may enter via ports providedin the lifter blades or shredders.

Although the plugs 70, 72 of waste have been described as being formedby controlling the rate of flow of waste through the processing plant, acontrol paddle may be additionally or alternatively provided which isoperated to directly stoke the plug to provide the inlet/outlet seal.Although a chemical additive has been described as being added to thewater supply, such could be separately added to the waste. Although thewaste in the wet feed preparation drum has been described as beingheated by adding water and steam permeating back through the system fromthe thermal processor, additional heating means could be provided.Although an air lock slide valve has been described at the entrance tothe hopper, this could be omitted and/or a similar seal provided at theoutlet to the outlet chamber 60. Although a cone section has beendescribed at the outlet to the thermal processor, this could be omitted.Although the various vessels have been described as being thermallyclad, such may comprise special heat retentive steel or a combination ofboth. Although the drum and processor have been illustrated as havingsubstantially the same cross-section, they could have differentdiameters. For example, the drum could have a smaller cross-section thanthe processor, enabling a greater proportion of hot air and steam withinthe processor. Although a specific pre-treatment of the waste has beendescribed with reference to FIG. 1, this stage of the treatment couldalso be varied to provide near consistent quality of shreddedhomogenized MSW. Also, the treated waste being discharged from theoutlet chamber 60 of the thermal processor may be further treated by theaddition of water, if for example the cellulosic pulp's end use requiresa wetter pulp.

While the invention has been described in detail in terms of a specificembodiment thereof, it will be apparent that various changes andmodifications can be made therein by one skilled in the art withoutdeparting from the scope thereof.

1-30. (canceled)
 31. An apparatus for treating municipal solid waste(MSW) comprising a moisture supply for adding moisture to said MSW, anon-pressurized feed preparation drum, a non-pressurized thermalprocessor located down-stream of said feed preparation drum, feedingmeans for conveying moistened MSW to be treated continuously throughsaid drum then said processor, agitating means for mixing the MSW in thefeed preparation drum, moisture evaporation means in the thermalprocessor for substantially turning the moisture in the MSW to steam tocook the MSW, and agitating means for mixing the MSW in the thermalprocessor.
 32. An apparatus as claimed in claim 31, wherein the drum andprocessor are provided in-line in substantially the same plane.
 33. Anapparatus as claimed in claim 32, comprising a buffer storage hopperlocated upstream of the feed preparation drum for receiving MSW to betreated and providing a column of MSW to be fed into the feedpreparation drum, the buffer storage hopper having a push floor feederat its base for directing MSW into the feed preparation drum.
 34. Anapparatus as claimed in claim 32, comprising a discharge chamber locatedbetween the feed preparation drum and thermal processor for receivingmoistened MSW discharged from the feed preparation drum and providing aplug of moistened MSW at entrance to the thermal processor, thedischarge chamber having a push floor feeder at its base for directingsaid moistened MSW into the thermal processor.
 35. An apparatus asclaimed in claim 32, comprising a thermal processor discharge chamberlocated downstream of the thermal processor for receiving the cooked MSWfrom the thermal processor and for providing a plug of cooked MSW at theoutlet of the thermal processor, the thermal processor discharge chamberhaving a push floor feeder at its base for directing MSW out of theapparatus.
 36. An apparatus as claimed in claim 34, comprising stokingmeans for maintaining the plug of MSW.
 37. An apparatus as claimed inclaim 31 comprising a shredder.
 38. An apparatus as claimed in claim 31,wherein the agitating means for mixing the MSW in the drum or processorcomprises means for rotating the drum or processor.
 39. An apparatus asclaimed in claim 38, wherein the agitating means comprises a tiltingmechanism for tilting the drum or processor.
 40. An apparatus as claimedin claim 31, wherein the wet-feed preparation drum is adapted to beinclined with respect to horizontal plane whereby entrance to the drumis in a lower plane that exit to the drum.
 41. An apparatus as claimedin claim 31, wherein the drum or processor comprises internal liftingblades.
 42. An apparatus as claimed in claim 31, the interior of saidthermal processor tapers inwardly towards its exit.
 43. An apparatus asclaimed in claim 31, comprising an explosion vent for said thermalprocessor.
 44. An apparatus as claimed in claim 31 comprising ventingmeans adapted to remove excess heat and steam from the apparatus.
 45. Anapparatus as claimed in claim 44, wherein said venting means returnssaid excess steam to said moisture supply.
 46. An apparatus as claimedin claim 44, comprising a scrubber for cleaning said excess steam. 47.An apparatus as claimed in claim 44, comprising an air separator forremoval of any entrained airborne matter from said vented heat andsteam.
 48. An apparatus as claimed in claim 31, comprising means forheating the moisture supply.
 49. An apparatus as claimed in claim 31,wherein the moisture evaporation means is a source of hot gases.
 50. Anapparatus as claimed in claim 31, comprising tilting means for adjustingthe tilt of the drum and/or processor.
 51. A process for treatingmunicipal solid waste (MSW) comprising the steps of: adding moisture tothe MSW; conveying the MSW through a non-pressurized feed preparationdrum; agitating said MSW as it is conveyed through the drum to moistenthe MSW and to initilize pulping of organic matter present in the MSW;conveying the moistened MSW from the drum to a non-pressurized thermalprocessor; agitating said MSW as it is conveyed through the thermalprocessor; and heating the moist MSW in the processor to substantiallyturn the moisture to steam to cook the MSW.
 52. A process as claimed inclaim 51, comprising the additional step of stocking the moistened MSWupon exit from the feed preparation drum to provide a plug of MSW atentrance to the thermal processor.
 53. A process as claimed in claim 50,comprising the additional step of stocking the cooked MSW upon exit fromthe thermal processor to provide a plug of MSW at outlet of the thermalprocessor.
 54. A process as claimed in claim 50, comprising the step ofshredding and homogenizing the MSW before conveying it through the feedpreparation drum.
 55. A process as claimed in claim 54, wherein the MSWis shredded to have no dimension greater than 200 mm.
 56. A process asclaimed in claim 50, comprising the additional step of heating themoisture before it is added to the MSW.
 57. A process as claimed inclaim 50, the step of heating is heating the MSW to up to 400° C. at theoutlet to the thermal processor and up to 100° C. at the inlet to thethermal processor.
 58. A process as claimed in claim 50, comprising thestep of monitoring the MSW in the various stages of the process andadjusting the rate of conveying the MSW based on the level of the MSW ata selected stage of the process.
 59. An apparatus for the treatment ofmunicipal solid waste (MSW) constructed and adapted to operatesubstantially as described herein with reference to and as illustratedin the drawings.
 60. A process for the treatment of municipal solidwaste (MSW) adapted to operate substantially as described herein withreference to the drawings.